doom their children to the status of "potato eaters." To prevent this outcome the family sold the estate and embarked as a unit for America. With the family savings every child could have a farm in America as large as the paternal estate in Germany (39). In the 1840's, the German emigration consisted largely of such parents and their unmarried sons who moved into the rural areas of America.* In still other families the father and the older sons chose to remain while the younger sons sought their fortunes elsewhere, in factory jobs, in the growing urban centers of Europe, or abroad in America. A system of primogeniture may serve to keep the family estate intact, but in a situation of expanding family size it may serve to divide the family. One can readily picture the tensions within families in Ireland, Germany, Italy, and eastern Europe throughout the 19th century as men quarreled over whether to sell their estates and migrate as a family, whether to divide the estates into uneconomical units, or whether to turn the land over to older sons while the younger ones migrated. If the family is to migrate, should one member go ahead and the others follow later, or should the entire family migrate at once? If one son turns his patrimony over to the others, how should he be compensated? If the entire estate is to be sold, and the family to emigrate abroad, what shall be done with the elderly and the sick? Shall they be taken along or shall they be sent to live with the relatives who remain? If new agricultural techniques are employed, new crops introduced, or profits from agriculture rise, then there may be little migration. Under these conditions, fragmentation may take place without a drop in income from father to son. Clark has cited a number of historical examples of transformations of agriculture under conditions of rapid population growth—6th century B.C. Greece, 16th century Holland, Britain in the latter part of the 18th century, Japan at the end of the 19th century, and perhaps India today (31, pp. 72-73). In these instances, Clark argues, population growth compelled peasants to change their methods of cultivation and economize in the use of land. There are a variety of ways in which peasants have adapted to changes in the ecological balance within the framework of traditional agriculture—by cultivating what had previously been considered marginal land, by the elimination of pasture lands, by engaging in supplementary occupations, by adopting a few new crops (such as potatoes), or simply by living with a lower income. Which response to changing family size is made by peasants-the cultivation of new lands, the adoption of new agricultural techniques and crops, the fragmentation of landholdings, or migration—can all be influenced by government policy or the opportunities which exist outside of agriculture. ^Whether any member of the family chooses to move at all under conditions of declining agriculture can have significant political consequences, too. For an examination of the issue-when does a population rebel rather than migrate-see (40).